Frontiers of Science and Technology | Brief Analysis of PTFE Lamination Process

The film-coated filter material used in the bag-type dust removal industry can not only achieve near-zero emissions, but also because the film is non-sticky and has a small friction coefficient, the powder cake will fall off automatically, ensuring long-term stability of the equipment resistance, so it can give full play to the bag-type dust collector. Superiority, is the ideal filter material choice.

A new type of filter material formed by compounding a layer of polytetrafluoroethylene (PTFE) film on the surface of ordinary filter material, which is PTFE Membrane filter material. The PTFE membrane is equivalent to playing the role of a "primary dust layer". The material exchange is carried out on the surface of the membrane, and it can be effectively filtered at the beginning of use. The unique three-dimensional network structure of the film makes it impossible for dust to pass through, and there is no risk of pore blockage. This type of filtering is called "surface filtering".

At present, the main PTFE coating processes on the market are: adhesive method and high temperature hot pressing process.
Adhesive method: This method mainly adheres the film and the base cloth together through the adhesion of the adhesive. The process is convenient to operate, and the cost of the laminating machine is low, and it is a laminating process that is widely used at present.
Difficulties: Polytetrafluoroethylene (PTFE) has excellent high temperature resistance, weather resistance, chemical corrosion resistance, low surface tension and other characteristics, but because PTFE contains extremely strong C-F bonds and atoms reinforced C-C bonds are completely symmetrical. Linear polymer, resulting in very low surface tension of PTFE and its film, the surface is not easy to wet, and it is difficult to be compatible with other substances.

Methods: The currently developed and researched adhesives that can directly bond low surface energy fluorine-containing materials mainly include solvent-based adhesives using organic amine complexes as initiators, hot-melt adhesives containing thermoplastic fluoropolymers, and water-based adhesives. adhesive. Through different gluing processes, a layer of adhesive is coated on the base fabric to bond the PTFE film and the base fabric together.

Disadvantages: In the process of laminating, there will be problems such as whether the base cloth is evenly glued and the adhesive is easy to carbonize at high temperature. Because the adhesive will block the microporous structure of the PTFE film, it will cause the air permeability of the coated filter material to decrease, and under the condition of high temperature use, the adhesive will melt or even carbonize, which will further lead to the blockage of the micropores of the film and the desorption of the filter material. membrane, affecting the service life of the membrane filter material.

High-temperature hot-pressing process: The high-temperature hot-pressing lamination process is to first treat the base fabric or PTFE film with a special surface treatment, and then laminate the film and base fabric together under a certain pressure and temperature.